Despite being on the market for nearly a decade, direct-to-consumer (DTC) genetic testing continues to be controversial among experts and raises concerns among health care providers and regulatory agencies.

The NIH-funded "Impact of Personal Genomics (PGen) Study" addresses these concerns by empirically measuring the perceptions and tracking the behaviours of individuals who have received DTC genetic testing from two separate companies.

Research from this large-scale prospective study has already generated numerous new scientific reports.

These findings shed light on who seeks testing and why, and how they respond to the results that they receive.

The latest results from the PGen Study were published in the Journal of Clinical Oncology.

This was an analysis of how customers respond to common cancer risk information (not Mendelian cancer risks like BRCA1/2), and was led by Stacy W. Gray, MD, City of Hope National Medical Center with senior author Robert C. Green, MD, MPH of Brigham and Women's Hospital, Broad Institute and Harvard Medical School.

In this analysis, Gray and colleagues specifically looked at personal genomic testing for cancer risk, and found that 12-24 percent of individuals received "elevated" cancer risk estimates for prostate, breast and colon cancer.

Despite learning they were at increased risk for these common cancers, most customers did not report changing their diet, exercise, supplement use, advanced care planning or cancer screening in comparison to the customers who learned they were at average or lower risk.

The one exception is men who received elevated prostate cancer risk estimates as some of these men changed their vitamin and supplement use more than those at average or reduced risk.

This counter-intuitive finding may have resulted because the increased cancer risks reported to the customers were very modest, and because the kind of individual who purchases DTC genetic testing may already have been very proactive about their health and using other available screening tests for cancer.

"These results suggest that people are not over-reacting to very modest cancer risks in DTC genetic testing. This is consistent with some of our other findings showing that early adopters of DTC genetic testing understand the limited predictive impact of DTC results and do not over-react either emotionally or in terms of generating additional and unnecessary medical expenses," said Green, director of the Genomes2People Research Program.

The PGen Study cohort is a group of more than 1,600 consumers who purchased personal genomic tests prior to the imposition of FDA restrictions in 2013 from 23andMe and Pathway Genomics (Pathway has since changed their business model and no longer provides DTC testing).

In addition to sharing their actual test results with investigators, participants completed surveys before receiving their results and again two weeks and six months after receiving their results.

The surveys also presented mock results to determine if consumers could accurately interpret them.

"There has been a tremendous amount of interest and opinion expressed about the potential benefits, harms and costs associated with personal genomic testing, and most of it has been speculative. The PGen Study provided us with a goldmine of data on consumer expectations, how consumers interpret, recall and experience their results, how their results impact their state of mind, what actions they take after testing, and how all of these factors change over time," said Green.

"As far as many of the speculated risks and harms around direct-to-consumer genomic testing, we have not uncovered evidence that they are either common or severe," added Scott Roberts, PhD, of the University of Michigan's School of Public Health, and joint principal investigator of the PGen Study with Green. "Although we have found some areas where informed consent for testing and communication of results could be improved, our data suggest most consumers find their results as potentially useful in informing future health decisions and advance planning."

Source: Brigham And Women's Hospital